Electronic devices, such as cellular telephones, cameras, automobiles, and computers, commonly use image sensors to capture images. A typical CMOS (complementary metal-oxide-semiconductor) imager circuit includes a focal plane array of pixels, and each pixel includes a photo-sensor, such as a photogate or photodiode for accumulating photo-generated charge in a portion of the substrate.
Digital images are constructed using data from the pixels. In some cases, only a portion of the entire pixel array is used to construct the final output image. For example, images captured with a wide angle lens (e.g., a fisheye lens) provide the advantage of capturing a larger field of view. The primary image, however, will often appear distorted (non-rectilinear) and may include more data than is necessary. The image may be processed, using spatial transforms, to produce a rectilinear secondary image, which keeps a portion of the pixel signals and discards the remaining portion. In general, conventional systems that read out the entire pixel array for each primary image require increased processing, increased memory, and increased power capabilities.